package com.ea.trade.thirdpart.hele.utils;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * 文件名称: Base64.java
 * 类名: Base64
 * 日期: 2015年8月27日
 *
 * 功能描述：Base64算法实现
 */
public final class Base64 {

	/** 文件读取缓冲区大小 */
	private static final int CACHE_SIZE = 1024;

	static private final int BASELENGTH = 128;

	static private final int LOOKUPLENGTH = 64;

	static private final int TWENTYFOURBITGROUP = 24;

	static private final int EIGHTBIT = 8;

	static private final int SIXTEENBIT = 16;

	static private final int FOURBYTE = 4;

	static private final int SIGN = -128;

	static private final char PAD = '=';

	static private final boolean fDebug = false;

	static final private byte[] base64Alphabet = new byte[BASELENGTH];

	static final private char[] lookUpBase64Alphabet = new char[LOOKUPLENGTH];

	static {
		for (int i = 0; i < BASELENGTH; ++i) {
			base64Alphabet[i] = -1;
		}
		for (int i = 'Z'; i >= 'A'; i--) {
			base64Alphabet[i] = (byte) (i - 'A');
		}
		for (int i = 'z'; i >= 'a'; i--) {
			base64Alphabet[i] = (byte) (i - 'a' + 26);
		}
		for (int i = '9'; i >= '0'; i--) {
			base64Alphabet[i] = (byte) (i - '0' + 52);
		}
		base64Alphabet['+'] = 62;
		base64Alphabet['/'] = 63;
		for (int i = 0; i <= 25; i++) {
			lookUpBase64Alphabet[i] = (char) ('A' + i);
		}
		for (int i = 26, j = 0; i <= 51; i++, j++) {
			lookUpBase64Alphabet[i] = (char) ('a' + j);
		}
		for (int i = 52, j = 0; i <= 61; i++, j++) {
			lookUpBase64Alphabet[i] = (char) ('0' + j);
		}
		lookUpBase64Alphabet[62] = '+';
		lookUpBase64Alphabet[63] = '/';
	}

	/* -------------------------------------
	 * public方法
	 * -------------------------------------*/

	/**
	 * 方法名称: encode
	 * 功能描述: Encodes hex octects into Base64
	 *
	 * @param binaryData Array containing binaryData
	 * @return String  Encoded Base64 array
	 */
	public static String encode(final byte[] binaryData) {

		if(binaryData == null) {
			return null;
		}

		int lengthDataBits = binaryData.length * EIGHTBIT;
		if(lengthDataBits == 0) {
			return "";
		}

		int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
		int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
		int numberQuartet = fewerThan24bits != 0 ? numberTriplets + 1 : numberTriplets;
		char encodedData[] = null;
		encodedData = new char[numberQuartet * 4];
		byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;

		int encodedIndex = 0;
		int dataIndex = 0;
		if(fDebug) {
			System.out.println("number of triplets = " + numberTriplets);
		}

		for (int i = 0; i < numberTriplets; i++) {
			b1 = binaryData[dataIndex++];
			b2 = binaryData[dataIndex++];
			b3 = binaryData[dataIndex++];
			if(fDebug) {
				System.out.println("b1= " + b1 + ", b2= " + b2 + ", b3= " + b3);
			}
			l = (byte) (b2 & 0x0f);
			k = (byte) (b1 & 0x03);
			byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
			byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
			byte val3 = ((b3 & SIGN) == 0) ? (byte) (b3 >> 6) : (byte) ((b3) >> 6 ^ 0xfc);
			if(fDebug) {
				System.out.println("val2 = " + val2);
				System.out.println("k4   = " + (k << 4));
				System.out.println("vak  = " + (val2 | (k << 4)));
			}
			encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
			encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
			encodedData[encodedIndex++] = lookUpBase64Alphabet[(l << 2) | val3];
			encodedData[encodedIndex++] = lookUpBase64Alphabet[b3 & 0x3f];
		}

		// form integral number of 6-bit groups
		if(fewerThan24bits == EIGHTBIT) {
			b1 = binaryData[dataIndex];
			k = (byte) (b1 & 0x03);
			if(fDebug) {
				System.out.println("b1=" + b1);
				System.out.println("b1<<2 = " + (b1 >> 2));
			}
			byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
			encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
			encodedData[encodedIndex++] = lookUpBase64Alphabet[k << 4];
			encodedData[encodedIndex++] = PAD;
			encodedData[encodedIndex++] = PAD;
		} else if(fewerThan24bits == SIXTEENBIT) {
			b1 = binaryData[dataIndex];
			b2 = binaryData[dataIndex + 1];
			l = (byte) (b2 & 0x0f);
			k = (byte) (b1 & 0x03);
			byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
			byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
			encodedData[encodedIndex++] = lookUpBase64Alphabet[val1];
			encodedData[encodedIndex++] = lookUpBase64Alphabet[val2 | (k << 4)];
			encodedData[encodedIndex++] = lookUpBase64Alphabet[l << 2];
			encodedData[encodedIndex++] = PAD;
		}
		return new String(encodedData);
	}

	/**
	 * 方法名称: decode
	 * 功能描述: Decodes Base64 data into octects
	 *
	 * @param encoded string containing Base64 data
	 * @return byte[] Array containind decoded data.
	 */
	public static byte[] decode(final String encoded) {

		if(encoded == null) {
			return null;
		}

		char[] base64Data = encoded.toCharArray();
		// remove white spaces
		int len = removeWhiteSpace(base64Data);

		if(len % FOURBYTE != 0) {
			return null;//should be divisible by four
		}

		int numberQuadruple = (len / FOURBYTE);
		if(numberQuadruple == 0) {
			return new byte[0];
		}

		byte decodedData[] = null;
		byte b1 = 0, b2 = 0, b3 = 0, b4 = 0;
		char d1 = 0, d2 = 0, d3 = 0, d4 = 0;
		int i = 0;
		int encodedIndex = 0;
		int dataIndex = 0;
		decodedData = new byte[(numberQuadruple) * 3];

		for (; i < numberQuadruple - 1; i++) {
			if(!isData((d1 = base64Data[dataIndex++])) || !isData((d2 = base64Data[dataIndex++]))
				|| !isData((d3 = base64Data[dataIndex++]))
				|| !isData((d4 = base64Data[dataIndex++]))) {
				return null;
			}//if found "no data" just return null
			b1 = base64Alphabet[d1];
			b2 = base64Alphabet[d2];
			b3 = base64Alphabet[d3];
			b4 = base64Alphabet[d4];
			decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
			decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
			decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);
		}

		if(!isData((d1 = base64Data[dataIndex++])) || !isData((d2 = base64Data[dataIndex++]))) {
			return null;//if found "no data" just return null
		}

		b1 = base64Alphabet[d1];
		b2 = base64Alphabet[d2];
		d3 = base64Data[dataIndex++];
		d4 = base64Data[dataIndex++];
		if(!isData((d3)) || !isData((d4))) {//Check if they are PAD characters
			if(isPad(d3) && isPad(d4)) {
				if((b2 & 0xf) != 0)//last 4 bits should be zero
				{
					return null;
				}
				byte[] tmp = new byte[i * 3 + 1];
				System.arraycopy(decodedData, 0, tmp, 0, i * 3);
				tmp[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
				return tmp;
			} else if(!isPad(d3) && isPad(d4)) {
				b3 = base64Alphabet[d3];
				if((b3 & 0x3) != 0)//last 2 bits should be zero
				{
					return null;
				}
				byte[] tmp = new byte[i * 3 + 2];
				System.arraycopy(decodedData, 0, tmp, 0, i * 3);
				tmp[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
				tmp[encodedIndex] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
				return tmp;
			} else {
				return null;
			}
		} else { //No PAD e.g 3cQl
			b3 = base64Alphabet[d3];
			b4 = base64Alphabet[d4];
			decodedData[encodedIndex++] = (byte) (b1 << 2 | b2 >> 4);
			decodedData[encodedIndex++] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
			decodedData[encodedIndex++] = (byte) (b3 << 6 | b4);
		}
		return decodedData;
	}

	/**
	 * 方法名称: encodeFile
	 * 功能描述: 
	 * <p>
	 * 将文件编码为BASE64字符串
	 * </p>
	 * <p>
	 * 大文件慎用，可能会导致内存溢出
	 * </p>
	 *
	 * @param filePath 文件绝对路径
	 * @return String
	 * @throws IOException 
	 * 
	 */
	public static String encodeFile(final String filePath) throws IOException {
		byte[] bytes = fileToByte(filePath);
		return encode(bytes);
	}

	/**
	 * 方法名称: decodeToFile
	 * 功能描述: 
	 * <p>
	 * BASE64字符串转回文件
	 * </p>
	 *
	 * @param filePath 文件绝对路径
	 * @param base64 编码字符串
	 * @throws IOException 
	 *
	 */
	public static void decodeToFile(final String filePath, final String base64) throws IOException {
		byte[] bytes = decode(base64);
		byteArrayToFile(bytes, filePath);
	}

	/* -------------------------------------
	 * private方法
	 * -------------------------------------*/

	private static boolean isWhiteSpace(final char octect) {
		return (octect == 0x20 || octect == 0xd || octect == 0xa || octect == 0x9);
	}

	private static boolean isPad(final char octect) {
		return (octect == PAD);
	}

	private static boolean isData(final char octect) {
		return (octect < BASELENGTH && base64Alphabet[octect] != -1);
	}

	/**
	 * 方法名称: fileToByte
	 * 功能描述: 
	 * <p>
	 * 文件转换为二进制数组
	 * </p>
	 *
	 * @param filePath 文件路径
	 * @return byte[]
	 * @throws IOException
	 * 
	 */
	private static byte[] fileToByte(final String filePath) throws IOException {
		byte[] data = new byte[0];
		File file = new File(filePath);
		if(file.exists()) {
			FileInputStream in = new FileInputStream(file);
			ByteArrayOutputStream out = new ByteArrayOutputStream(2048);
			byte[] cache = new byte[CACHE_SIZE];
			int nRead = 0;
			while ((nRead = in.read(cache)) != -1) {
				out.write(cache, 0, nRead);
				out.flush();
			}
			out.close();
			in.close();
			data = out.toByteArray();
		}
		return data;
	}

	/**
	 * 方法名称: byteArrayToFile
	 * 功能描述: 
	 * <p>
	 * 二进制数据写文件
	 * </p>
	 *
	 * @param bytes 二进制数据
	 * @param filePath 文件生成目录
	 * @throws IOException 
	 * void
	 */
	private static void byteArrayToFile(final byte[] bytes, final String filePath) throws IOException {
		InputStream in = new ByteArrayInputStream(bytes);
		File destFile = new File(filePath);
		if(!destFile.getParentFile().exists()) {
			destFile.getParentFile().mkdirs();
		}
		destFile.createNewFile();
		OutputStream out = new FileOutputStream(destFile);
		byte[] cache = new byte[CACHE_SIZE];
		int nRead = 0;
		while ((nRead = in.read(cache)) != -1) {
			out.write(cache, 0, nRead);
			out.flush();
		}
		out.close();
		in.close();
	}

	/**
	 * 方法名称: removeWhiteSpace
	 * 功能描述: remove WhiteSpace from MIME containing encoded Base64 data.
	 *
	 * @param data the byte array of base64 data (with WS)
	 * @return int the new length
	 */
	private static int removeWhiteSpace(final char[] data) {
		if(data == null) {
			return 0;
		}
		int newSize = 0;
		int len = data.length;
		for (int i = 0; i < len; i++) {
			if(!isWhiteSpace(data[i])) {
				data[newSize++] = data[i];
			}
		}
		return newSize;
	}
}
